Drive mechanism for a stepping switch



Aug. 3, 1965 J. s. ROBERTS 3,193,965

DRIVE MECHANISM FOR A STEPPING SWITCH Original Filed June 50, 1961 2 Sheets-Sheet 1 INVENTOR. James S. Roberts L020 8 Barry Attorneys Aug. 3, 1965 J. s. ROBERTS DRIVE MECHANISM FOR A STEPPING SWITCH 2 Sheets-Sheet 2 Original Filed June 50, 1961 NOE INVENTOR. James S. Roberts L020 8 Barry Attorneys United States Patent 3,198,955 DRTVE MEQHANESM FOR A STEPPING SWITCH S. Roberts, Brooltiield, Wis, assignor to Milwaukee Chemist ii; Company, Inc, Miiwaukee, Wis. riginal application June 30, 1961, Ser. No. 121,241. Divided and this application Dec. 14, 1962, Ser. No.

7 Qiaims. or. 367-141) This application is a division of application Serial No. 121,241 filed June 30, 1961.

This invention relates to sequence timing devices and more particularly relates to that class of electrical switch ing means known as interval timers. The invention has special reference to a stepping means for step by step operation of a memory device to control a sequence of events.

Stepping switches as heretofore commonly known in the art include a memory device on which is structurally coded a predetermined program. The coded structure ordinarily represents and actuates a desired sequence of switching operations. Each switching ope-ration in turn controls one or more events such as operating a machine, admitting liquid into a tank, closing a valve or the like. The coded structure of the memory device accomplishes this by manipulating switches which the structure engages or disengages in step by step advancement of the memory device.

As a general rule the memory device of such stepping switches is an intermittently rotated member. The intermittent rotation moves the member a fraction of a circle each time, dwells at the new position for some predetermined period of time, then moves to another position in like fashion and dwells again. This moving and dwelling during rotation is termed stepping. The memory device nust be positively located after each step in order to assure the proper actuation of the function switches at each interval.

The primary object of this invention is to provide an improved system for intermittently advancing a drum type timer.

Another object of the present invention is to provide a steeping system for a drum type timer which advances t e drum at a fast rate in order to provide a positive action in the function switches.

A further object of the present invention is to provide ping system which positively locates the memory .ce at each station.

These objects are accomplished by mounting a Geneva type advancing mechanism within the confines of a drum memory device. The memory device is advanced by intermittently energizing a timing motor located within the drum which drives a pin wheel in the advancing mechanism. The pin Wheel provides a positive and fast motion in the Geneva wheel as well as locating the wheel at a dead center position. The pin wheel is also used to set up a holding circuit for the motor so that it will drive the pin wheel through a complete step each time the dium is to be advanced. This arrangement provides a certain amount of free or lost motion both at the beginning and end of a step which allows the motor to build up sufficient force to move the Geneva wheel through each step quickly. A detent mechanism may be provided in the advancing mechanism to stop the pin wheel at the exact dead center at the end of each step.

r-ther objects, advantages and features will become apparent from the following description when read in conjunction with the associated drawings. Throughout the drawings, the same reference numerals are used to designate the same parts and the usual convention isomloyed of showing the electrical apparatus in the position assumed when all of the electricity is cut off from the circuits. In the drawings:

FIG. 1 is a simplified schematic and partially exploded perspective electromechanical view of the invention.

FIG. 2 is a cross sectional elevation through the drum showing the gear train along the shaft.

FIG. 3 is a cross sectional end view through 3a3a of FIG. 2 showing the relationship of the dead centering means of the Geneva drive.

Referring to the drawing, drum motor 2%], dead centering means 24, and gear train 22 are shown in position to drive drum 2. The whole is arranged so that the drum 2 may be easily removed and so that the motor and gear train is encased within the drum when it is mounted on the shaft as disclosed in the above mentioned copend ing application.

Referring now to FIG. 2, drum 2 is shown secured by removable means such as a plurality of screws 50 to a pair of hubs 52, 54 which are spaced apart along a nonrevolvable shaft 56. The shaft 56 has a flatter portion 5% to which the motor 2% is secured by any suitable means such as screws, brackets or the like. The shaft has a hollow portion 65 preferably disposed at the inboard end adjacent the hinge means for swinging the drum out of the bracket to change drums and thereby install a new program. VV-ires for the motor 2% and various switch means associated with the dead centering means 24 are led in to the inside portion of the drum through the hollow portion as.

The hub 54 is revolvably mounted on the shaft 56 by any suitable bearing prefer-ably a frictionless bearing such as a ball bearing, indicated generically as 62. Hub 54 is maintained in its position on the shaft by a pair of spaced apart rings, 63, 64 which are secured to the shaft by set screws 65 and 66.

The hub 52 is mounted in a partly similar fashion, but uses the gear train 22, and the supports thereof in lieu of a ring such as 63 to guard against axial displacement toward the other hub.

The gear train is supported from the shaft by support means generically denoted as 7% which is secured to the shaft and so constructed as to allow various portions of the gear train to revolve relative both to the support means and the shaft 55. The support means (and the gear train for that matter) is secured to the shaft by a pair of spaced apart bear train supporting hubs 71, 72 which are respectively secured to the shaft by set screws 73, 74. A plurality of washers 75 are disposed between the support hubs and adjacent revolving members, one of such washers being used to space the drum hub 52 from the support 71.

An idler support plate 77 is secured to the hub 71 by any suitable means such as screws or welding or may be formed integrally therewith. A dead centering switch support plate 78 is supported in spaced apart relation to the idler plate by means of a plurality of tubular spacers 79, the whole being secured together by a corresponding plurality of nuts and bolts 39.

A motor support plate $2 is secured to the hub 72, or may be fashioned integrally therewith. The motor may be supported from this plate if desired. The motor plate 82 has an aperture 83 through which the motor output shaft 21 extends.

The motor output shaft is connected directly into th gear train by means of a Geneva wheel arrangement which includes a Geneva pin wheel 84 having in the preferred embodiment a pair of 180 spaced apart pins 85 secured thereto by any suitable means such as force fitting, welding, or the like. The reason a pair of pins is used is that the Geneva wheel 86 is a tenpoint drive having ten slots therein.

The dead centering timing Wheel 111 is formed as a plate mounted to rotate in unison with the Geneva pin wheel.

A sleeve 87 is disposed between the Geneva wheel and a shaft mounted gear 83 in such fashion that the gear and Geneva wheel rotate together. Appropriate bearing means 89 are provided to revolvably support from the shaft the Geneva wheel, gear, and sleeve. With this construction, the gear 88 and the Geneva wheel 86 rotate in unison. i

A driven drum gear 99 is secured to the hub 52 by any convenient means such as keying or a forced fit in order that the drum rotates in unison with the gear 91). A pair of idler gears 91, 22 connects the gear 88 to the gear 91 The idler gears are revolvably supported from the support means 70, preferably from a single shaft 93 to which they are both secured to rotate in unison. The securing means may advantageously comprise idler set screws 9-1 which engage flatted portions on the shaft 93.

The shaft 93 is revolvably supported by a pair of bearings 95, $6. The idler shaft bearings Q5, are respectively supported in the idler support plate 77 and the switch support plate 78. The bearings may conveniently be shaped as bushings so that the idler gear 92 is maintained in axial alignment with its mating gear 88.

In review, as the motor 20 rotates, the Geneva pins 85 drive the Geneva wheel as which revolves in characteristic intermittent Geneva fashion and causes gear 38 to move in like fashion. Idler S 2 is supported in meshing engagement with gear 8% and responds to the motion, transmitting it to the idler gear 91 which then, being in mesh with the drum gear 90, drives the latter. Thus, a speed reduction is obtained and at the same time the requisite intermittent motion for obtaining a stepping action is provided. In the preferred embodiment, it is desired to step the drum one 6 increment of rotation in response to an 180 rotation of the motor. Thus, a 30 to 1 reduction is preferably provided. Consistent with this, the holes for receiving the various pins are spaced at 6 intervals around the periphery of the drum.

When it is desired to remove the drum and replace it with one having a different program, the screws 50 are removed and the drum moved axially until it is free of the hubs.

In the upper central part of FIG. 2 is shown a detent mechanism for mechanically positioning the drum and the motor at dead center. This comprises a detent ball 97 which is mounted in a hole at the end of an externally threaded hollow detent case 98 which is screwed into a corresponding threaded hole in the motor support plate 82. A detent lock nut 99 further secured the detent assembly in place.

Although not shown, the hollow detent case contains a compressed helical spring which biases the detent ball 99 into frictional engagement with the face of the Geneva pin wheel 84. If desired, small depressions can be formed at dead center position in the face of 87, which depressions are engaged at the end of rotation by the detent ball.

FIG. 3 illustrates a cross sectional view across section Zia-3a of FIG. 2 and shows in what position the dead centering switch 108, 107 is secured relative to the dead centering wheel 11 1. The dead centering switch is screwed to the switch support plate 78 by a pair of screws 78a and 73b. The arm 114 of the dead centering switch is thereby positioned with respect to the dead centering wheel 111 so that switch 1G8 is closed when off dead center and open at dead center as elsewhere described in greater detail. The switch 1118, 167 may be any commercially available type of microswitch.

The timing wheel 111 in the preferred embodiment is different in minor details from that shown schematically in FIG. 1, principally in that lobes 112 and 113 are provided in lieu of the notches 112, 113 shown in FIG. 1. It will be observed in FIG. 2 that the Geneva drive pins 85 are spaced apart so that one is entering a Geneva slot at the same time the other is leaving the preceding Geneva slot. This further promotes positive positioning. Dead center is preferably arranged so that the pins are in the positions shown in FIG. 3 when at dead center. This permits the driving pin 85 which is entering the slot to promote a stepping operation having a low initial and final rotational velocity, with a high intermediate velocity to get a sharp break in control functions (i.e. break occurs during intermediate). When the driving pins 85 are positioned as shown in FIG. 3 (i.e. dead center), the drum is also as dead center. The phrase dead centering refers to the drum as well as the motor insomuch as the two are connected by virtue of the Geneva wheel and related gearing.

The operation of the advancing mechanism is shown in FIG. 1 where drum 2 has been rotated so that pin P3 has closed due of the timer selection switches 1115. This completes a circuit from power source 102, through switch 1127, switch 1% to timer 1% which determines the length of the timer interval. At the end of the interval, timer arm will momentarily close switch arm 1139 with switch contact T1-2 closing a circuit from power source 192' to motor 20. Energization of the motor will cause timing wheel 111 to rotate opening switch 1117 and closing switch 198 which sets up a holding circuit for the motor from power source 102 and opens the circuit to timer The motor will run until switch 114 drops into notch 1112 opening the holding circuit and closing the circuit to the timer 104. The cycle is then repeated as described in the aforementioned application.

The advancing mechanism is operated by the electrical circuit generally shown in FIG. 1. This circuit is shown by way of example only since the interval time control is interchangeable with the pulse system shown in Roberts copending application Serial No. 121,241 filed June 30, 1961. In the circuit shown, as drum 2 is stepped through a cycle of operations, pins P3 actuate timer selection switches 106 (13) or 106 (L4). A circuit will be established from power source 162 through switch 107, the selected switch 106 (L3) in this case and timer motor 1104.

The timer motor will drive arm 111 around at a predetermined rate until switch arm 109 is closed momentarily with switch contact T1-2. A momentary circuit is then set up from power source 162' through contact T1-2 to motor 20. The initial motion of the motor will move timing wheel 111 off of dead center. It can be seen that the timing wheel closes the dead centering switch 108 setting up a holding circuit from power source Hi2 through switch 108 to motor 20. Simultaneously with the closing of switch 1108, switch 167 is opened stopping the operation of the selected timer 104. In FIG. 1 the notches 112, 113 are shown for actuating the switch arm 114 which may also comprise the lobes of timing cams as shown in FIGS. 2 and 3.

The drive motor will run until switch arm 114 drops into the next notch on the wheel opening switch 1&3 and closing switch 167. The drum will be advanced to the next step and pin P3 will set up the circuit for the proper timer motor 164. The cycle is then repeated.

Although only one modification of the present invention is shown and described, it should be apparent that various changes and modifications can be made within the scope of the appended claims.

I claim:

1. A drive system for an interval timer comprising a shaft,

a memory device rotatably mounted on said shaft,

motor means secured to said shaft, a Geneva wheel rotatably mounted on said shaft, reduction gear means connecting said wheel to said memory device, 7

and rotatable means operatively connected to said motor means for advancing said Geneva wheel in a step by step manner, whereby the motion of said Geneva wheel is transferred to said memory device.

2. A drive system according to claim 1 including holding switch means for controlling the operation of said motor means,

said rotatable means including cam means for actuating said switch means to thereby set up a holding circuit condition to complete each step of the drum.

3. A drive system according to claim 2 wherein said rotatable means includes a pair of pins positioned parallel to the axis of rotation of the rotatable means on diametrically opposite sides thereof, only one of said pins being operative during each step of the Geneva wheel.

4. A drive system for an interval timer comprising a rotatable memory device,

a drive mechanism for advancing said memory device in a step by step manner,

said drive mechanism including a disc having a number of equally spaced radially directed slots therein and a wheel having a pair of pins parallely arranged on diametrically opposite sides of said wheel,

said wheel being positioned to rotate so that one of said pins will enter one of the slots of said disc in each half revolution of said wheel,

the disc being advanced a predetermined angular distance each half revolution of the wheel.

5. A drive system according to claim 4 wherein said drive mechanism includes a detent means for stopping said wheel at a dead center position at the end of each step.

6. A sequence timer comprising a memory device,

a step by step drive mechanism,

reduction gear means operatively connecting said drive mechanism to said memory device for advancing said memory device at a predetermined rate, with respect to the motion of said drive mechanism,

said drive mechanism including 2. Geneva wheel and a pin wheel,

a motor for intermittently rotating said pin wheel,

and a pulse source actuated at the end of each time interval for initiating the operation of said motor to advance the memory device.

7. A sequence timer according to claim 6 including a holding circuit for said motor and switch means for bolding said circuit closed during each step of the memory 20 device,

said pin wheel including cam means for actuating said switching means.

No references cited.

25 LLOYD MCCOLLUM, Primary Examiner. 

1. A DRIVE SYSTEM FOR AN INTERVAL TIMER COMPRISING A SHAFT, A MEMORY DEVICE ROTATABLY MOUNTED ON SAID SHAFT, MOTOR MEANS SECURED TO SAID SHAFT, A GENEVA WHEEL ROTATABLY MOUNTED ON SAID SHAFT, 